Optical switch

1. An optical switch including at least one input port and at least one output port, comprising: an optical demultiplexing element that demultiplexes an optical signal from the at least one input port into wavelength-separated optical signals; at least one first optical deflection element that deflects the wavelength-separated optical signal incoming from the optical demultiplexing element to change a traveling direction thereof for each wavelength; a second optical deflection element that deflects the optical signal incoming from the first optical deflection element to be output to at least one of the output ports; and an optical multiplexing element that multiplexes the wavelength-separated optical signals incoming from the second optical deflection element, wherein: the first optical deflection element and the second optical deflection element deflect the incident optical signal in a switch axis direction perpendicular to a wavelength dispersion axis direction of the optical demultiplexing element and the optical multiplexing element, the first optical deflection element and the second optical deflection element are formed of liquid-crystal elements each having phase distribution forming a curved surface in the switch axis direction, and a beam waist of the optical signal exists in a position located midway between the first optical deflection element and the second optical deflection element in the switch axis direction.

2. The optical switch according to claim 1 , wherein at least one of the first optical deflection element and the second optical deflection element includes a spatial phase modulation element having a plurality of microscopic phase modulation elements.

3. An optical switch including at least one input port and at least one output port, the optical switch comprising: an optical demultiplexing element that demultiplexes an optical signal from the at least one input port into wavelength-separated optical signals; at least one first optical deflection element that deflects the wavelength-separated optical signal incoming from the optical demultiplexing element to change a traveling direction thereof for each wavelength; a second optical deflection element that deflects the optical signal incoming from the first optical deflection element to be output, to at least one of the output ports; and an optical multiplexing element that multiplexes the wavelength-separated optical signals incoming from the second optical deflection element, wherein: the first optical deflection element and the second optical deflection element deflect the incident optical signal in a switch axis direction perpendicular to a wavelength dispersion axis direction of the optical demultiplexing element and the optical multiplexing element, the first optical deflection element and the second optical deflection element are formed of liquid-crystal elements each reflecting the optical signal, a reflecting surface of each of the first optical deflection element and the second optical deflection element has phase distribution forming a curved surface in the switch axis direction, and a beam waist of the optical signal exists in a position located midway between the first optical deflection element and the second optical deflection element in the switch axis direction.

4. An optical switch including at least one input port and at least one output port, the optical switch comprising: an optical demultiplexing element that demultiplexes an optical signal from the at least one input port into wavelength-separated optical signals; at least one first optical deflection element that deflects the wavelength-separated optical signal incoming from the optical demultiplexing element to change a traveling direction thereof for each wavelength; a second optical deflection element that deflects the optical signal incoming from the first optical deflection element to be output to at least one of the output ports; and an optical multiplexing element that multiplexes the wavelength-separated optical signals incoming from the second optical deflection element, wherein: the first optical deflection element and the second optical deflection element deflect the incident optical signal in a switch axis direction perpendicular to a wavelength dispersion axis direction of the optical demultiplexing element and the optical multiplexing element, each of the first optical deflection element and the second optical deflection element includes a MEMS mirror array with each mirror having a curvature in the switch axis direction, and a beam waist of the optical signal exists in a position located midway between the first optical deflection element and the second optical deflection element in the switch axis direction.

5. The optical switch according to claim 1 , comprising: at least one first optical element that converts all of the optical signals incoming from the at least one input port into parallel light in the wavelength dispersion axis direction; at least one second optical element that converts a shape of beam in all of the optical signals incoming from the at least one input port to form parallel light in the switch axis direction; at least one third optical element that changes the optical signal incoming from the optical demultiplexing element to convergent light in the wavelength dispersion axis direction to form a beam waist on the first optical deflection element; at least one fourth optical element that changes the optical signal incoming from the first optical deflection element to parallel light in the wavelength dispersion axis direction; at least one fifth optical element that changes the optical signal incoming from the fourth optical element to convergent light in the wavelength dispersion axis direction to form a beam waist on the second optical deflection element; at least one sixth optical element that changes the optical signal incoming from the second optical deflection element to parallel light in the wavelength dispersion axis direction; at least one seventh optical element that converts all of the optical signals from the optical multiplexing element to convergent light in the wavelength dispersion axis direction, and converts a shape of beam to be coupled to at least one of the output ports; and at least one eighth optical element that converts all of the optical signals from the optical multiplexing element to allow a main light beam of the optical signal to converge in the switch axis direction for conversion of an optical path to be coupled to at least one of the output ports.

6. The optical switch according to claim 5 , wherein: each of the first optical deflection element and the second optical deflection element includes an optical deflection element that reflects the optical signal; the third optical element is shared with the fourth optical element; and the fifth optical element is shared with the sixth optical element.

7. The optical switch according to claim 6 , comprising: a ninth optical element that is placed between the third optical element shared with the fourth optical element and the fifth optical element shared with the sixth optical element to invert and reflect an image of the optical signal in the wavelength axis direction, wherein the third optical element shared with the fourth optical element is also shared with the fifth optical element and the sixth optical element.

8. The optical switch according to claim 7 , wherein the third optical element, the fourth optical element, the fifth optical element and the sixth optical element are formed of the same optical element reflecting the optical signal.

9. The optical switch according to claim 5 , wherein the first optical element and the second optical element input each of the optical signals incident from the at least one input port into the optical demultiplexing element at the same angle.

10. The optical switch according to claim 5 , wherein the first optical element, the second optical element, the third optical element, the fourth optical element, the fifth optical element and the sixth optical element each enter the optical signal to be sent to the at least one output port, into the optical multiplexing element at the same angle for the same wavelength.

11. The optical switch according to claim 1 , wherein: the at least one input port and the at least one output port are connected respectively to optical-beam forming devices including optical waveguides formed on a substrate; the optical-beam forming device comprises: connection waveguides, the number of which is equal to the number of the input ports or the number of the output ports, a first slab waveguide connected to the connection waveguides, array waveguides connected to the first slab waveguide and having an optical path difference which is small to such an extent that interference characteristics in a signal wavelength band are negligible, and a second slab waveguide connected to the array waveguides; a surface of the substrate is placed in a direction parallel to the switch axis; and a length of the second slab waveguide in an optical axis direction is set in a fixed position from an output end of the optical waveguide.

12. The optical switch according to claim 1 , wherein: the at least one input port and the at least one output port are each connected to an optical-beam forming device including optical waveguides formed on a substrate; the optical-beam forming device comprises: connection waveguides, the number of which is equal to the number of the input ports or the number of the output ports, a first slab waveguide connected to the connection waveguides, array waveguides connected to the first slab waveguide and having an optical path difference which is small to such an extent that interference characteristics in a signal wavelength band are negligible, and a second slab waveguide connected to the array waveguides; a surface of the substrate is placed in a direction parallel to the switch axis; and a boundary between the array waveguides and the second slab waveguide is formed of a curved surface.

13. The optical switch according to claim 11 , wherein: a connection point line between the connection waveguides and the first slab waveguide differs between an input optical beam forming device which is the optical beam forming device to which the input ports are connected, and an output optical beam forming device which is the optical beam forming device to which the output ports are connected; and points constituting the connection point line in the output optical beam forming device are placed in a midpoint position between points of the connection point line in the input optical beam forming device.

14. The optical switch according to claim 12 , wherein: a connection point line between the connection waveguides and the first slab waveguide differs between an input optical beam forming device which is the optical beam forming device to which the input ports are connected, and an output optical beam forming device which is the optical beam forming device to which the output ports are connected; and points constituting the connection point line in the output optical beam forming device are placed in a midpoint position between points of the connection point line in the input optical beam forming device.